Elihu thomson



(No Model.)

B. THOMSON.

REGULATOR FOR DYNAMO ELECTRIC MACHINES. No. 269,606. Patented De .26, 1882.

TTEST: INVENTDBI 7 UNITED STATES PATENT CEEICE.

ELlHU THOMSON, OF NEW BRITAIN, CONNECTICUT, ASSIGNOR TO THE AMERICAN ELECTRIC COMPANY, OF SAME PLACE.

REGULATOR FOR DYNAMO-ELECTRIC MACHlNES.

SPECIFICATION formingpart of Letters Patent No, 269,606, dated December 26, 1882,

(No modeLl To all whom it may concern Be it known that I, ELIHU THOMSON, a citizen ot'the United States, and a resident of New Britain, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Regulators for Dynamo-Electric Machines, of which the following is a specification.

My invention relates to the adjustment of the commutators of dynamo-electric machines, the object being to secure a more perfect adaptation'of the machine to changes in the external resistance.

My invention is'designed more particularly forapplicationto'theclassot'machinespatented to me jointly with E. J. Houston by Letters Patent ot' the United States dated May 13, 1880, and described in other and subsequent patents, the distinguishing characteristic of which machine is an armature wound with three bobbins or coils, three of the similar ends of which are connected together, while the opposite three ends are separately connected to the three segments ofa commutator. Ido not, however, confine my invention to this particular class'of machines, as itis possible to apply it to other forms or constructions of machine. with beneficial results. In previous patents I have described a regulator in which the commutator-brushes are adjusted forward in the direction of rotation Whenever a decrease in the external resistance occurs, so that the current generated will remain constant; and my present invention may be regarded as an improvement upon the class of regulators referred to.

The invention consistsin employing a set of collecting-brushes, adapted to embrace a portion' of the circumference of the commutator on opposite sides thereof, and in so constructing the parts that when the brushes are moved forward the space covered by the same 011 both sides of the commutator will be diminished, the diminution occurring by reason of a more rapid movement at one terminal that at the other of the brush-space.

One of the methods of carrying my invention into practice consists in employing two pairs of commutator-springs, the two springs of each pair being diametrically opposite one another. The two pairs, being mounted on independentrocker-arms and bearing upon the commutator-cylinder at different positions oircumi'erentially, are connected to suitable mechanism, whereby they may be adjusted together, but at different rates of movement, so that one pair ot'brushes will move faster than the other,a nd thus diminish the space between the two brushes on the same side of the commutatol.

Figure 1 is a side view ot'a commutator constructed according to my invention, and Fig. 2 is a plan view thereof.

K K K represent the three commutatorsegmeuts of my three coil machine, separated from one another by straight slots parallel to the shaft or running at a slight angle thereto.

3 y 1 p represent two pairs of com in utatorbrushes, the pair 3 y of which bear upon the commutatator-cylinder at dlametrically-opposite points, as do also the pair 1 1 I) E are independent rocker-arms for the two pairs, each arm being mounted in any suitable manner-as; for instance, loosely on the shaft of the machine, so that either arm may move independently of the other. the pair of brushes 1 y or the forward brushes are mounted upon the arm E, while the rear pair of brushes, y 3 are mounted on the arm I).

H represents a lever, pivoted at h and connected by a link, E, with the armature-lever M of an electro-magnet, R, the strength of which is made to increase with any increase in the strength of the general current of the machine, and vice versa, by any suitable arrangement-as, for instance, by placing said magnet directly in said general circuit after the plan described in my prior patents.

The armature is here shown as perforated and the pole-piece as tapered or of paraboloidal form, so as to give practically constant attractive effects with thesa-me current at all positions of the armature with relation to the pole. This feature does not, however, form any portion of my present invention, and the lever might be moved by other means, elther automaticallyorbyhand. ThearmsDFarecon- As shown,

nected to the lever H at ditterentdistances from its fulcrum by links b b, so that, as will be apparent, the rear pair of brushes will move faster than the forward pair, the ratio of movement being approximately six to seven, although this ratio may be varied, and may also be changed according to circumstances. The two brushes 3 f upon the same side of the commutator are electrically connected together, so as to constitute a compound brush, and are insulated from the two upon the opposite side, which are similarly connected together, one of the compound brushes thus formed being the negative and the other the positive brush of the machine. The angle between the two brushes of each compound brush and the circumferential comm utator-space covered is normally thirty to forty degrees, according to the strength of the machine. When the strength of the magnet increases in response to a decrease in the external resistance of the working-circuit, the brushes y y are adjusted forward, so as to decrease the current collected, as set out in my prior patents, while at the same time the commutatorspace covered by the compound brush y 3 is decreased, owing to the more rapid movement of the brush 3 the length of time during which two of the commutator-segments are simultaneously in contact with the compound brush is at the same time shortened, this tending also to a diminution in the strength of the current.

1 do not limit myself to any particular mechanical devices forgiving the required difl'erential movement ot'the brushes, the invention consisting broadly in shortening the commutator-space covered by the collecting-brushes simultaneously with their forward movement. Other mechanical constructions, whereby the commutator-space covered by the collecting brush or brushes may be shortened simultaneously with. their forward movement, will readily suggest themselves.

What I claim as my invention is- 1 1. The combination, with the commutatorcylinder for a dynamo-electric machine, of an adjustable collecting-brush and means for automatically shortening the collecting extent of said brush simultaneously with its forward adjustment.

2. The combination, with the commutatorcylinder in a dynamo-electric machine, oftwo differentially-moving sets of springs moving differentially with relation to one another in the manner described, so as to shorten the comn'nltetor-space covered by them simultaneously with their forward movement.

3. The combination, with the three-segment commutator in a three-coil-armaturc machine of the kind described, of automatically-adjustable commutator-brushes constructed, in the manner described, to shorten the circumferential commutator-space covered simultaneously with their forward movement.

4. The combination, with a three-coil armature machine and its three-segment commutator, of two pairs of com mutator-brushes differentially adjusted in the manner described, so that the space between them is shortened simultaneously with their forward movement.

5. The combination, with the pairs of commutator-brushes mounted on independent supports, oian adj LlSllllglCVGI, to which the brushsupports are connected at different points, the support for the rear brushes being connected thereto at a point farther from the fulcrum than the support tor the forward pair.

6. The combination, with theleverE, of the links I) I), attached thereto at different points from the fulcrum, and the yokes D F, each supporting at its opposite ends two comn'iutatorbrushes.

Signed at New Britain, in the county of Hartford and State of Connecticut, this 23d day ofSeptember, A. D. 1882.

ELIHU THOMSON.

Witnesses W. MCGRATH, Jr., C. M. MOREY. 

